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#Post#: 7157--------------------------------------------------
building a heavy car!
By: Tinworm Date: July 2, 2022, 9:01 am
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Oh crikey, I have started weighing parts of my kart because I
have been worrying about the fact that I have made my structural
stuff in steel, and wondering how extra heavy I have ended up
making everything.
My chassis, wheels, engine, TAV and rear axle come to 61.5Kg.
Apart from my front axle tube, that is my heaviest stuff out of
the way, but I still have my aluminium to go and loads of bits.
And I am not a lightweight driver! My car is going to struggle
to get off its marks!
What does your kart weigh and if you have run if, how did it
cope with the weight, especially if it was the heavier end of
the range?
#Post#: 7158--------------------------------------------------
Re: building a heavy car!
By: RhysN Date: July 2, 2022, 10:20 am
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Voisin was 192 lbs all up. (Folks there reckon the scales were
reading heavy) ie could really be lighter.
#Post#: 7159--------------------------------------------------
Re: building a heavy car!
By: Tinworm Date: July 2, 2022, 10:46 am
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so was that a very light car, on average?
(circa 87kg)
#Post#: 7162--------------------------------------------------
Re: building a heavy car!
By: RhysN Date: July 2, 2022, 3:11 pm
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One of the lightest Peter.
#Post#: 7163--------------------------------------------------
Re: building a heavy car!
By: Tinworm Date: July 2, 2022, 3:24 pm
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well that is reassuring then, Rhys.
When Stefan put 150Kg as an all up maximum, I wonder if that is
with an expectation of the car being able to move ?
I am going for as low as I can, not exceeding 100Kg, hopefully.
#Post#: 7164--------------------------------------------------
Re: building a heavy car!
By: peterL Date: July 2, 2022, 4:40 pm
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It's a subject I was looking at last weekend, and came to a
couple of conclusions.
Firstly there's a fixed overhead of weight that it's very hard
to avoid, I weighed wheels, motor, tav, rear axle, disc brake,
chainwheel, and front axle, and they come in somewhere North of
60kgs. The 'average' US karts seem to be coming in at around
115kgs, (250lbs.)
So the only real scope for weight reduction is to keep the
chassis and body somewhere between 30 and 55kgs. So there's not
a huge difference if you consider the all up weight of car and
driver is around 200kgs.
Secondly there is a probably a greater difference in driver
weights, I'm around 80kgs, some of our colonial cousins are
20kgs above that, so there's probably a bigger difference in
driver weights than karts.
So I stopped worrying too much about it, kart weight differences
can be in the region of 10%, with tuning there can be 20% or
30% difference in engine output while still being under the 10hp
guidelines, so you can always tweak the motor or play with
gearing if you feel you're not competitive.
I too am watching the pounds, (or kgs), and did a quick audit on
my build to date last week that gave the following rough
estimates if it's any use, I used bathroom scales, so it's
probably a bit flaky at the moment.
Engine 14.6, wheels 22.8, tav brake disc hubs 8, rear axle,
chainwheel, hubs 8.6, front axle 5, steering column and wheel
1.8, giving a fixed overhead I can do little about of 60.8kgs
The chassis rails, crossmembers, floors and front spring perch
are 19.6, the nosecone and scuttle 4.6, and my indulgence of a
reverse box is 3.6
This puts me currently at 88.5 kilos, with side panels, a tail
section, bonnet, pedals, brake caliper, chain and probably a
battery to complete, so my target of 100kg is likely to be
exceeded, but probably only by about 10% I'm not going to
stress too much about it, I think it's going to end up somewhere
on the middle of the pack weight wise. I'm just hoping that my
centre of gravity will be lower than most, - I will get it
built first, then worry about where I can drill holes to lighten
it later.
Peter
#Post#: 7170--------------------------------------------------
Re: building a heavy car!
By: Andy_B Date: July 4, 2022, 7:17 am
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Weighed mine recently - 124kg all in. I am unfortunately 128kg.
Engine was on the dyno at 9hp so not sure what the wheel hp is
but if I drive it like I stole it I can just about keep up - but
I win the slalom!!!! every cloud ;D
As Peter said, don't stress too much, build a safe Cyclekart and
if all else fails drill holes
Andy
#Post#: 7171--------------------------------------------------
Re: building a heavy car!
By: Tinworm Date: July 4, 2022, 8:29 am
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Hi Peter, thanks very much for the detail and advice.
Very grateful to you and Andy. Reckon I will stop stressing.
cheers Pete
#Post#: 7172--------------------------------------------------
Re: building a heavy car!
By: peterL Date: July 4, 2022, 12:49 pm
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And Andy's comment about drilling holes is very accurate, quite
by coincidence I spent the day working on the bonnet of the
Seven, the rear former, in 18mm MDF, started life at 1318
grammes,
[attach=1]
A bit of work with bandsaw, and a drill, and it's now down to
346 grammes
[attach=2]
so nearly a kilogram taken out of one piece alone, even drilling
the holes took out 71 grammes.
As a result of this I'm putting the rest of the kart on a diet,
to see what can be taken out safely.
Peter
#Post#: 7173--------------------------------------------------
Re: building a heavy car!
By: Tinworm Date: July 5, 2022, 2:32 am
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really beautiful work, Peter
and take the point about holes
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